Modes
Transparent operating mode
Digi XBee® 3 802.15.4 RF Module User Guide
75
Transparent operating mode
Devices operate in this mode by default. The device acts as a serial line replacement when it is in
Transparent operating mode. The device queues all UART data it receives through the DIN pin for RF
transmission. When a device receives RF data, it sends the data out through the DOUT pin. You can set
the configuration parameters using Command mode.
Transparent operating mode is not available when using the SPI interface; see
.
Serial-to-RF packetization
Data is buffered in the incoming serial buffer until one of the following causes the data to be
packetized and transmitted:
1. No serial characters are received for the amount of time determined by the
RO
(Packetization
Timeout) parameter. If
RO
= 0, packetization begins when a character is received.
2. The maximum number of characters that will fit in an RF packet is received. There are a
number of factors that determine payload size. You can query the
to determine the maximum payload size based on current configuration. For
more information, see
3. The Command mode Sequence,
GT
+
CC
+
GT
, (including spaces) is received; this is any data in
the serial receive buffer received before the sequence is transmitted. For more information,
see
If the device cannot immediately transmit (for instance, if it is already receiving RF data), the serial
data is stored in the serial receive buffer. The data is packetized and sent at any
RO
timeout or when
NP
bytes are received.
If the serial receive buffer becomes full, hardware flow control must be implemented in order to
prevent overflow (loss of data between the host and device).
API operating mode
Application programming interface (API) operating mode is an alternative to Transparent mode. It is
helpful in managing larger networks and is more appropriate for performing tasks such as collecting
data from multiple locations or controlling multiple devices remotely. API mode is a frame-based
protocol that allows you to direct data on a packet basis. It can be particularly useful in large
networks where you need control over the operation of the radio network or when you need to know
which node a data packet is from. The device communicates UART or SPI data in packets, also known
as API frames. This mode allows for structured communications with serial devices.
For more information, see
.
Command mode
Command mode is a state in which the firmware interprets incoming characters as commands. It
allows you to modify the device’s configuration using parameters you can set using AT
commands. When you want to read or set any parameter of the XBee 3 802.15.4 RF Module using this
mode, you have to send an AT command. Every AT command starts with the letters
AT
followed by the
two characters that identify the command and then by some optional configuration values.
The operating modes of the XBee 3 802.15.4 RF Module are controlled by the
setting,
but Command mode is always available as a mode the device can enter while configured for any of the
operating modes.
